Adjustable drawing curve



April 1939- w. MOSES 2,155,169

ADJUSTABLE DRAWING CURVE Filed April 1, 1937 INVENTOR. WA D E M0 8 E SBY I 1/1 ATTORNEYS.

Patented Apr. 18, 1939 UNITED STATES PATENT OFFICE ADJUSTABLE DRAWINGCURVE Application April 1, 1937, Serial No. 134,353

6 Claims.

This invention relates to drawing instruments having a ruling edgeadapted to be adjustably curved and more particularly to an instrumentof this type having an improve-d surface construction.

I am familiar with prior drawing instruments adapted to be adjusted toprovide curved ruling surfaces of varying contours comprising a hollowbody of flexible material such as rubber having a core of lead orsimilar material and a strip of spring metal. However, the material inthese prior devices has been formed of relatively stiff rubber with thedrawing edge abutting the surface upon which the curved line is to bedrawn and it has been necessary to separate the material into segmentsto permit proper bending. Additionally, rubber has a tendency to smearor erase graphite and due to its affinity for ink, has a tendency tosmear an ink line.

Other prior devices of this general type with which I am faniiliar haveattempted to incorporate a flexible ruling surface with the rubber bodybut due to the difference in bending characteristics of such materialand rubber body, together with the difference in expansioncharacteristics under thermal change, they have been unsatisfactoryafter a short period of use.

I have devised an adjustably curved drawing instrument of this generaltype wherein a ruling surface is provided on each edge of the body andspaced from contact with the surface upon which a line is to be drawnand wherein the entire surface of the body is coated with a stretchablemetallic substance overcoming the natural tendency of a rubber surfaceto impede passage of a pencil or ruling pen drawn therealong due tominimizing the frictional resistance. This protective coating largelyeliminates any tendency to erase or smear pencil lines already drawn andacross which the instrument may be moved. I have further provided acorrugated bearing surface for the instrument preventing any tendency toslip during use and a corrugated top surface providing a firm grippingsurface for the draftsman.

It is an object of my invention, therefore, to provide an improved,adjustably curved drawing instrument comprising a rubber body having ametallic surface.

Another object of my invention is to provide a drawing instrument of theabove type having dual ruling edges, each ruling edge being spaced fromcontact with the surface upon which the instrument rests, and one rulingedge being spaced a greater distance from the surface than the other.

Another object of my invention is to provide a drawing instrument of theabove type which offers relatively little resistance to the passage of apencil or ruling pen drawn along a ruling edge portion.

Another object of my invention is to provide a drawing instrument of theabove type having a corrugated top to form a gripping surface.

Another object of my invention is to provide a drawing instrument of theabove type which is economical to manufacture and assemble.

Other objects of my invention and the invention itself will becomeincreasingly apparent from a consideration of the following descriptionand drawing wherein: 15

Fig. 1 is a plan view of an adjustably curved drawing instrumentembodying my invention;

Fig. 2 is a transverse sectional view taken along the lines 2-2 of Fig.1 illustrating the manner of using the low drawing edge;

Fig. 3 is a transverse sectional view showing a modification of myinvention;

Fig. 4 is a transverse sectional view showing a further modification ofmy invention, and

Fig. 5 is a view similar to Fig. 2 showing the manner of using the highdrawing edge.

Referring now to the drawing, I have indicated generally at ill, ahollow body of flexible material, preferably formed of extruded ormolded rubber which is generally rectangular in crosssection and isprovided with a longitudinally extending low ruling edge I l and a highruling edge l2. The top and bottom surfaces of the body If! arepreferably corrugated as indicated at l3 and [4 respectively. Insertedwithin the body is a 35 core [5 formed of lead or similar material whichmay be bent to a desired form and which will retain such form, the leadcore preferably being substantially square in cross-section. Alsodisposed within the body It] and on each side of the 40 core I5, areflexible strips l6-|6 which permit the core Hi to easily movetherebetween and resist any tendency to bend the instrument other thanin one plane.

Additionally, the strips l6 insure a smooth curve and prevent a sharpirregular bend which might otherwise occur.

The material of body I0 is preferably prepared in lengths such as 3 andis then dipped in a solution containing a metallic powder, preferablyaluminum. Various solutions, well known in the art are available but Ipreferably employ a clear vehicle having a nitro-cellulose base combinedwith a plasticizer and solvent suitable for aluminum powder. Thematerial is then suspended and allowed to dry for a period such as 24hours and it will be found that a smooth uniform coating results whichis yieldable with the rubber and has no tendency to crack or peeldespite long and severe usage. The material is then cut into a desiredlength and core l5 and strips 16 are inserted therein with the materialends of the body l0 extending somewhat beyond the ends of the core andthe strips.

Although I preferably employ aluminum powder, I contemplate that variousother finely divided metals or hard material might be employed whichwould adhere to and yield with the material.

These materials may be applied in either powder or flake form, micabeing an example of a flake form material having suitable protectionproperties and providing a smooth surface. The flake material need notentirely cover or coat the material surface but should cover a majorportion of the surface.

I have found that when rubber material is treated as above described,that a pencil or ruling pen may be drawn easily therealong making asmooth curved line and since the point of the pencil or pen ismaintained out of contact with the rubber body there is no danger ofsmearing a drawn line. However, since the rubber surface illustrated haslittle affinity for ink and will not tend to erase or smear graphite,inadvertently drawing the instrument across a line or projecting theruling pen point inwardly to contact the body will not cause the ink torun as normally occurs.

It will be apparent that if an extra low drawing edge is desired thatthe position of the instrument may be reversed and the drawing edge I2will occupy the position !2', indicated in dotted lines in Fig. 5.

Referring now to Fig. 3, I have shown a modification of my inventionwherein the body I0 is provided with a longitudinally extending groove20 within which is inserted a closely coiled spring 2|. The groove 20 isformed to provide overhanging edge portions 22 engaging spring 2! andmaintaining it in assembled relation and I contemplate that the springends may be anchored to the body in any suitable manner as by forming astraight portion at each end projected through the body Walls and bondedtherein. Additionally, I may secure the spring 2! to the body at spacedpoints intermediate the ends by clip members bonded to the body walls.The spring is easily bendable with the body and provides a ruling edgeover which a pen or pencil may be easily drawn.

Referring now to Fig. 4, I have shown a further modification of myinvention generally similar to that illustrated in Fig. 3 but wherein adove-tail groove 25 is provided in the body and a flexible ruling edgeelement 26 is inserted therein. The element 26 is preferably formed ofCelluloid but any suitable similar material may be used.

Although I have only illustrated one insert in the modifications ofFigs. 3 and 4, I contemplate that both ruling edge portions may beprovided by inserts, if desired.

Although I have shown and described a preferred embodiment of myinvention, I contemplate that numerous and extensive departures may bemade therefrom without departing from the spirit of my invention or thescope of the appended claims.

Having thus described my invention, what I claim is:

1. An adjustably curved drawing instrument comprising a rubber bodyhaving a longitudinally extending hole therethrough, the outer surfaceof the body having a coating containing a metallic powder, a lead or thelike rod Within the body hole, a pair of metal strips one on each side,of the rod, limiting bending of the rod and body to a given plane, and aruling edge portion extending longitudinally of the body spaced from thebase of the body.

2. An adjustably curved drawing instrument comprising a rubber body,having a longitudinally extending hole therethrough, a lead or the likerod inserted in the hole, a metal strip on each side of the rod limitingbending of the body to a given plane, and the base of the body beingcorrugated to provide a plurality of longitudinally extending supportingribs.

3. An adjustably curved drawing instrument comprising a rubber bodyhaving a longitudinally extending aperture therethrough, a lead or thelike rod within the aperture, a pair of resilient metal strips one oneach side of the rod limiting bending of the instrument to a givenplane, the outer surface of the body having a coating containing ametallic powder whereby a drawing instrument may be easily drawntherealong, and each side of the body being provided with alongitudinally extending ruling edge spaced at difp ferent distancesfrom the base of the instrument.

4. An adjustably curved drawing instrument comprising a rubber bodyhaving a longitudinally extending aperture therethrough, a lead or thelike rod inserted in the aperture, a pair of metallic strips one on eachside of the rod limiting bending of the body to a given plane, and thetop and bottom surfaces of the body being provided with longitudinallyextending ribs forming gripping surfaces.

5. An adjustably curved drawing instrument comprising a rubber bodygenerally square form in cross-section, having a longitudinallyextending aperture therethrough, a lead or the like rod within theaperture generally square-form in cross section, a pair of metallicstrips one on each 6. An adjustable curve drawing instrument dcomprising an elongated rubber body, a soft metallic core within saidbody, a comparatively hard metal strip on each side of said core forconfining the bending of said body to a given plane,

a, coating containing a metallic powder on the outer surface of saidbody and a bendable ruling edge extending longitudinally of said body.

WADE MOSES.

